1. Field of the Invention
This invention relates generally to the field of trace gas measurement and more particularly to a method of determination of actual gas values by storing and transmitting polynomials.
2. Description of Related Art
Remote gas sensor units are known in the art and can communicate measured gas concentration values over cables, powerline carrier, or RF systems back to a central location. However, various sensor types including heated metal oxide sensors have a tendency to drift and may require postprocessing to determine accurate gas concentrations. Therefore, if a remote unit simply reports a simple concentration determined by, say sensor resistance, the value reported may not be accurate.
Prior art systems containing remote sensors have typically reported either a derived gas concentration value based an empirical formula relating sensor resistance, or conductance, to concentration, or have just reported a raw resistance or conductance value back to a central location where a formula, or some empirical, method is used to compute gas concentration.
What is badly needed is a method of computing gas concentration values from measured sensor values in the presence of drift and variations caused by ambient temperature or humidity. In addition, the method should make it easy to perform such computations at the central location in systems where there are numerous remotes. The method must account for calibrated sensor and electronic conditions in each remote without putting an overwhelming computation burden on the remote.